Field of the Invention
The present invention relates to a metal base substrate for a semiconductor device, a power module including the metal base substrate, and a method for manufacturing the metal base substrate.
Description of the Background Art
In the field of power electronics or the like, a metal substrate having a semiconductor chip mounted thereon is conventionally used to secure heat dissipation properties for heat generated in the semiconductor chip while being electrically insulated from the semiconductor chip, for example.
For example, in a case where a copper plate is used as a metal substrate, aluminum (or aluminum alloy) is rolled on one side (surface on the side on which an insulating layer is formed) of the copper plate to form a cladding base plate, in order to improve adhesion properties (adhesion strength) between the copper plate and the insulating layer formed on the copper plate. A liquid epoxy resin is applied on the cladding base plate to form the insulating layer, to thereby obtain a metal base substrate. The metal base substrate is disclosed (for example, see Japanese Patent Application Laid-Open No. 6-350213 (1994)).
In Japanese Patent Application Laid-Open No. 6-350213 (1994), the liquid epoxy resin is applied on the copper plate to form the insulating layer, so that the insulating layer fails to secure a thickness thereof and fails to maintain a withstand voltage. Moreover, a pinhole is formed in the insulating layer formed by the application of the liquid epoxy resin, whereby the withstand voltage may possibly decrease. Furthermore, the problem arises that a manufacturing process in manufacturing the configuration mentioned above becomes complicated.